In many situations, an efficient way to give a presentation or talk is to use electronically-presented slides. A presenter may typically press a button or use a handheld remote control to trigger transitions between slides. Sometimes, a presenter may recruit another person as an assistant to trigger the transition between slides based on the presenter's instructions. Such arrangements may not be ideal: an assistant may make mistakes while transitioning through slides by transitioning too early or too late; a remote control may be cumbersome and relies on a presenter remembering to press the appropriate button.